UPDATE: Manhunt Underway for Boston Marathon Bombing Suspects

Police on Friday morning surrounded a home in Watertown, Mass., the same suburban Boston community where authorities engaged in a firefight with 19-year-old Dzhokhar Tsarnaev and 26-year-old Tamerlan Tsarnaev, the two suspects in the deadly marathon bombings. The older Tsarnaev was killed in the firefight, while Dzhokhar Tsarnaev remains at large.

Two unidentified people were taken into custody at the Cambridge, Mass., home where Dzhokhar Tsarnaev and his older brother Tamerlan grew up, but they were not being described as additional suspects. Three dozen FBI agents were ringing the house.

Across the area, as police cars screamed down streets and helicopters hovered overhead, authorities urged the public to stay inside, their doors locked to anyone but a law-enforcement officer.

"There is a massive manhunt under way," Massachusetts Gov. Deval Patrick said. "We are asking people to shelter in place."

The lockdown initially affected more than 300,000 people in Cambridge, Watertown, Newton, Brighton, Allston and Belmont, but by 8 a.m., the entire city of Boston was paralyzed, officials said.

Watertown, where the second suspect was last seen, was the epicenter of the search. Frightened residents were trapped in their homes as convoys of heavily armed officers and troops arrived by the hour.

Harvard University, Boston University, the Massachusetts Institute of Technology and Emerson University were all closed and students were told to stay inside. Boston public schools were shuttered for the day.

The overnight violence began near MIT about five hours after the FBI released surveillance photos of the two men suspected of planting two bombs near the finish line of Monday's Boston Marathon, killing three and wounding 176.

As of now, a huge swath of the Boston metropolitan area has effectively been shut down this morning as residents are being asked to remain inside as the manhunt is underway. Dzhokhar Tsarnaev is still at large and wanted. And a third suspect may soon go into custody, as the Amtrak train he boarded has been stopped in Norwalk, Connecticut.

Overnight, MIT police officer Sean Collier was killed in a gun fight with two of the suspects.

Just in the last 24 hours, we've seen major developments in this case. Suspects have been identified, then two were named. And now, one is dead while another is being cornered in the Boston area and another may soon be arrested in Connecticut. It's amazing to see how quickly law enforcement is moving on this case.

However with that being said, there may still be other suspects/accessories to this crime at large. So far, this is still an active investigation. If you have any information that can lead to the capture of any suspects, contact the FBI immediately at this web site, or by calling 1-800-225-5324.